Vertical axis wind turbine with angled braces

ABSTRACT

An improved wind turbine comprises: (i) a turbine rotor with a support platform; (ii) a rotatable vertical shaft extending from or through that platform; (iii) at least one bearing for the shaft; (iv) a plurality of horizontally disposed, box-shaped wind catchment vanes connected about the shaft; and (v) a plurality of angled braces affixed to the platform for reducing wind force leverage effects and bearing wear.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.11/715,143, filed on Mar. 7, 2007 and entitled “Gravity-Flap,Savonius-Type Wind Turbine Device”, the disclosure of which is fullyincorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to the field of wind turbine devices,particularly those having a vertical axis of rotation. Moreparticularly, the present invention relates to a Savonius-type, windturbine device having a plurality of horizontally disposed, windcatchment vanes.

BACKGROUND OF THE INVENTION

1. Current Standard Wind Power Generators (ERDA-NASA)

The contemporary “industry gold standard” for the wind generation ofelectricity is a propeller design with a directional mechanism to keepit facing the wind—sometimes called an ERDA-NASA design. Over time, anumber of serious drawbacks and disadvantages of this design haveemerged which imply that this design may not be the best way to meet thechallenge of a rapidly accelerating demand for electrical power. Thesedeficiencies include the following:

a. While thought to be more efficient than its known alternatives mostlybecause of its high “tip-speed ratio” (explained below), the ERDA-NASAdesign may not derive sufficient power from the wind to make itparticularly cost-effective in the long run. It has been estimated thatgenerating enough power for a single residential dwelling may require apropeller at least 25 feet in diameter. Other estimates suggest thatvery large diameter designs, from 125-200 feet, may be needed to achieveoutputs in the 100 kilowatts-1000 kilowatts range. As size increases,production, installation, and maintenance costs rise very quickly. Also,given the higher stresses encountered with large, heavy units, failurerates rise making total replacement costs more likely. In addition, theefficient utilization of wind power by an ERDA-NASA unit requiressupplementary control mechanisms for: turning (or orienting) the unit;feathering its blades; and overspeed braking in high winds. Thesecontrol mechanisms use energy to operate—thus decreasing efficiency andfurther complicating design and production/maintenance costs. Units mustbe spaced apart roughly 10 times the rotor diameter to avoid turbulentinterference with each other. Consequently, wind farms will occupyconsiderable acreage for a sizeable number of units. For example, oneestimate requires 90 square miles for propellers 125 feet in diameter toproduce 100 megawatts. Thus, for any proposed wind farm site, it remainsa serious question whether ERDA-NASA units are economically feasible.

b. Safety considerations are also a factor. The higher tip speeds oftoday's propellers and greater dynamic strains and stresses on thematerials used to make same all contribute to metal fatigue, increasingthe risk of catastrophic failures. In addition, there are alreadyabundant concerns about the detrimental effects on wildlife, especiallybirds and migratory fowl and raptors. ERDA-NASA units located neardwellings, or on the tops of tall buildings, also pose potentiallyserious hazards to human and animal life as well as to property. Thetops of tall buildings are ideal sites for wind generators since windspeeds are proportionally greater at higher altitudes. In addition, thedesire to develop “green” buildings gives ample motivation forincorporating rooftop wind generators into future architectural plans.Unfortunately, ERDA-NASA generators may not be the best answer becauseof safety issues alone.

c. ERDA-NASA units are not able to utilize wind power efficiently over awide range of wind speeds. Current models of the ERDA-NASA wind turbinestypically operate at a preferred constant wind speed of 40 rpm in arange between 6 and 60 mph. The propeller blades are feathered toprevent damage in high winds (i.e., above 60 mph). Consequently, thereare significant energy losses at speeds in excess of 18 mph because thepropeller blades feather to maintain a preferred constant rotation at 40rpm. There are also significant energy losses at wind speeds less than18 mph because generator changes (changes in load) must be made to keepthat constant 40 rpm rotation. As wind speeds are highly variable,having such a narrow window of optimal wind velocities decreasesexpected efficiency.

d. High variation in wind speeds is not the only problem. The directionof wind current is itself in constant flux and unpredictable, especiallyin a small region over periods of great turbulence. Efficient windturbines must be able to rapidly adjust to sudden directional changesover a full range, i.e., 360 degrees. Today's ERDA-NASA devicesgradually reposition to take account of directional fluctuations, but byno means exhibit quick responsiveness to such directional changes.

e. Some wind generators have better applicability in smaller locationswith lower electrical power demands. Individual dwellings, recreationalvehicles, or marine uses may not readily accommodate smaller scaleERDA-NASA generators in terms of available physical space, safety and/oraesthetics.

Because of these disadvantages, alternatives to today's ERDA-NASA typegenerators should be sought for addressing the aforementioned problems.

2. Vertical-Axis Wind Turbines

Numerous patents have been granted in a category of wind turbines called“vertical-axis” turbines. These turbines are so-named because they havevanes or blades displayed outward from a vertically mounted, centralaxis, contrary to the horizontal axis of rotation for ERDA-NASAgenerators. The type of device installed on many home rooftops toimprove attic air circulation is a good example of a vertical-axisturbine. An anemometer is another. An immediate advantage of suchdevices is that they need not be rotated to always face the wind.Whatever direction the wind comes from, these devices can immediatelyabsorb wind energy and convert it to rotational power. Such devices aresometimes technically described as having their axis of rotationtransverse to the flow of fluid medium.

Previous designs of vertical axis windmills generally fall into twocategories, the Darrieus rotor and Savonius rotor types. Many variationsof the two have been designed over the years.

Darrieus-type wind turbines—One category of vertical-axis wind turbinesis based on the original Darrieus device (U.S. Pat. No. 1,835,018). Atraditional Darrieus rotor is essentially two or more long thin bladeswith their ends connected at the top and bottom to a vertically rotatingshaft. The cross-section of long blades has an airfoil shape, and thisaerodynamic feature provides the transformation of wind flow energy intorotational energy. Since the original Darrieus design, numerous deviceshave attempted to utilize aerodynamic thrust as the driving force forwind turbines.

Darrieus-type turbines suffer from several disadvantages. Many,especially those closely based on the original, are not self-starting.They require an auxiliary power source to reach operational speeds.Darrieus turbines have an outside rotor speed of 4 to 6 times the windspeed. Thus, in winds of 25 mph, the exposed knife blade-like rotorswill be traveling in excess of 100 mph. Such an arrangement is hardly“avian friendly,” and indeed might pose extreme hazards to life andproperty. Moreover, efficiency of the original Darrieus design has beenestimated to be only 30% to 40%. While alternative designs have meant toaddress some of these shortcomings, it is unlikely that anyDarrieus-type design that depends on converting aerodynamic thrust torotational energy will significantly improve these efficiency issues.The size of Darrieus-type turbines that could produce economicallyfeasible capacities of electricity would have to be quite large posingother challenges to construction, cost-effectiveness and aesthetics.

Savonius-type wind turbines—The original Savonius wind turbine, as shownin U.S. Pat. No. 1,697,574, was essentially a pair of opposing concavevanes rotating around a central vertical axis. The classic Savoniusrotors are open in the center and permit crossing fluid flow in anS-shape, past the inner edges of these rotating vanes. Later windturbine designs have increased the number of vanes, attached vanesdirectly to the central shaft or other blades to prevent crossing fluidflow, and/or incorporated fixed vanes (or “stators”) that do not rotatebut serve to advantageously direct wind towards the rotating vanes. Somedesigns have added rotating housings that orient to the direction ofwind for permitting wind flow only to those vanes presenting concavesurfaces and deflecting wind away from the vanes returning upwind. Thesehousings were meant to increase overall efficiencies. Still otherdesigns have included complex mechanisms for rotating or modifying thevanes when moving toward the wind so as to reduce resistance and improveefficiency. All such innovations share one common essential with theoriginal Savonius patent: they all depend on the fact that wind forceapplied to a rigid concave surface is greater than the same or lowerwind force (or static wind resistance) applied to a physicallyconnected, yet opposed rigid convex surface. This is evidenced in theoperation of a simple anemometer. The concave cup surface facing thewind will capture more wind power than the other cups presenting theirback convex surfaces causing the anemometer to rotate. As this is theessential energy transformation feature in all such designs, they willall be included in the category of “Savonius-type” designs for presentdiscussion purposes.

Due to this common design feature, most Savonius-type devices share amajor disadvantage of energy loss from “drag.” Drag is the resistanceresulting from moving a rigid surface against the wind or fluid medium.Because all of the vanes are surrounded by air when rotating, there isconstant drag that resists their movement even against the convex backsof downwind vanes moving away from the wind. When vanes are movingupwind and presenting their rear convex surface to the wind, the effectof drag is amplified by the added applied force of the wind. Theexistence of drag considerably reduces the efficiency of this type ofwind generator.

As noted above, ingenious devices have been designed to compensate fordrag. These devices may incorporate “stators” (stationary vanes arrangedsymmetrically around the rotor) to: (a) funnel wind flow into the vanesmoving downwind; and (b) deflect wind flow from vanes moving upwind.See, for example, U.S. Pat. No. 6,740,989. This can improve efficiencyby decreasing the amplification effect of drag caused by wind forcesacting on the vanes rotating upwind. Rotating housings that orient tothe direction of the wind accomplish the same thing permitting wind flowonly to the vanes moving downwind. See, for example, U.S. Pat. No.6,126,385. However, these designs do nothing to eliminate or diminishthe basic form of drag. Motion of the convex surfaces of the rigidrotating vanes against even stationary air in a stator- orhousing-protected rotor still produces drag, thus decreasing efficiency.Further ingenuity has produced devices with complex mechanisms thatdecrease the surface area of vanes not moving downwind. See generally,U.S. Pat. Nos. 4,494,007 and 7,094,017. Notable among these are openingand closing “clam-shell” designs, which open to catch the wind in adownwind course before closing to present less surface area during therest of the rotation. (For example, see U.S. Pat. No. 6,682,302).Similar to these are the “sail-furling” devices with vanes made of sailcloth. They are intended to open downwind, but quickly furl or fold forthe other part of rotation as per U.S. Pat. No. 6,655,916. See also,U.S. Pat. No. 5,642,983. These latter devices seem to effectivelyaddress the problem of drag, but at a cost. Rotational energy, or someother energy source, must be spent to operate these opening and closingmechanisms thereby compromising the efficiency of such devices. This isespecially true when those devices add a wind direction sensor forsynchronizing changes to the shapes of their vanes. It is doubtful thatsuch complex drag-compensating innovations produce an overall increasein efficiency. Intuitively, it should require more energy to modify vaneshapes by complex and/or synchronized mechanical means than would begained through drag reduction. In any case, such complex mechanisms addgreatly to manufacturing and maintenance costs in any commercialapplication.

Another serious disadvantage of the stator and protective-housingSavonius designs is the threat they pose to birds. The rotating vanesusually require minimal clearance between the edges of their stationarywind deflecting panels and vanes, creating a drastic sheering effect.From a bird's perspective, it would be as if someone had constructed ahuge “meat grinder” in its path. See, for example, U.S. Pat. Nos.5,380,149, 6,740,989 and 6,849,964. A rotating housing design offers aless severe sheer factor, but can still trap birds in its rotormechanism with little chance of passing through unscathed.

G. J. M. Darrieus, the inventor of the rotor discussed above, was amongthe first to note how the Savonius rotor suffers from a relativelylower, less efficient “tip speed ratio.” At best, the furthest outsidesection (i,e., part of the rotor furthest from the vertical axis ofrotation) for a Savonius device cannot exceed the speed of ambient windflow. This means that they have a maximal tip speed ratio of 1:1 ascompared to the ERDA-NASA or Darrieus rotor tip speed ratios of 3:1 orhigher. Higher tip speed ratios and rotation speeds allegedly make thelatter turbines more suitable for the efficient production ofelectricity. This serious deficit of the Savonius design, together withtheir problems with drag, have been used to condemn such devices asimpractical for purposes of serious power generation.

3. Gravity-Flap, Savonius-Type Wind Turbines

Compounding the above considerations produces a knockdown argumentagainst Savonius-type turbines. However, recent innovations in twoSavonius-type wind turbines make possible a design that may be able toaddress many of the above objections. The newer category makes use oflarge “flaps” held in a downward position by gravity to capture windforce. To be termed “gravity-flap Savonius wind turbines” in the presentinvention, they are shown and disclosed in U.S. Pat. No. 5,525,037 andPublished U.S. Application No. 20040086373. The basic principle of thesedevices is that gravity and the force of the wind will cause arectangular vane, hinged at the top, to naturally swing down. A frame orstopping mechanism blocks that vane from moving further when wind forcepushes against the vane thereby providing a driving power to the rotor.This vane is made of lightweight material, however. When it rotatesfurther so that its front face is no longer affected by the wind force,the vane is not blocked in that range of pivoting and can swivel up onits hinge to permit air to flow through. When the vane encounters airresistance on its rear surface, it pivots up and allows air or wind topass by unimpeded. This greatly reduces drag resistance even in staticair. When the vane travels through the upwind cycle, the wind forceacting on it can raise the vane even further, allowing more wind tospill through and further increasing turbine efficiency.

The inventor of latter published U.S. application has intuited somethingimportant about utilizing wind power. That disclosure includes adetailed assessment of the amount of wind force that may be captured andconverted to torque at the axis-hub. Using reasonable estimates andcalculations, the inventor opines that “incredible forces” may begenerated by such a device and the “leverage principle” it incorporates.What is lacking beyond one brief reference to how much horsepower anERDA-NASA generator requires to produce a certain amount of electricity,however, is a detailed comparison to see how that prior art gravity-flapSavonius design stacks up against a comparable ERDA-NASA turbine. Theomission of such a comparison is understandable since it is hard to seeon what basis the two can be compared. Many Savonius-type devices havebeen invented, all flying in the face of traditional considerations ofefficiency that condemn them as immediately stillborn. Hence, thequestion arises why there has been such stubborn persistence inimproving such devices. A possible answer is that most Savonius-typeinventors have shared the same belief that, in some way, Savonius-typewind turbines more successfully extract wind energy than their Darrieusor horizontal-axis turbine counterparts. The question remains whetherthis bare, unexpressed intuition can be articulated in such a manner toshow that it is not only plausible, but true.

4. Wind Energy Extraction-Effectiveness Vs. Efficiency

Some effort along these lines will now be made to conceptualize a basisfor an energy-extraction comparison of Savonius-type wind turbines withhorizontal-axis, particularly ERDA-NASA, wind turbines. This will takethe form of a thought experiment.

Suppose we are considering an arbitrarily selected vertical square plane100 ft.×100 ft., aligned transverse to the wind. The area of thishypothetical square area is 10,000 sq. ft. The amount of wind forcevaries according to altitude, drag coefficient, wind velocity squared,and surface area impacted. If we assume a sea level application with thevalue 0.0034, a drag coefficient of 1.5, and a wind velocity of 10knots, the force of the wind over the 10,000 sq. ft. area is:F _(w)=0.0034×1.5×(10)²×10,000=5100 pounds of wind force.

Given an ideal wind turbine in some possible world, all 5100 poundswould be capturable and translated into rotational energy. Of course,such a turbine cannot exist in our world. At best, any realSavonius-type vertical-axis turbine can present no more than 50% of itstransverse plane surface to the wind as a “working” surface—i.e., asurface capable of extracting wind energy. And only the surfaces ofrotor vanes moving downwind (roughly half of the vanes employed) willcapture wind energy. In practice, given the need for vane clearances andother structures, this capture area will be much less than 50%. So, letus suppose we construct a hypothetical Savonius-type turbine for the 100ft.×100 ft. square that presents only 35% of its surface in the squareas a “capture” area. That is, only 35% of the total 10,000 sq. ft. areaconsists of downwind moving vane surface area capable of extracting windenergy. Then, even if the working surfaces were 100% efficient, themaximum wind force the turbine could capture in principle would be 35%of 5100 pounds, or 1785 pounds. In practice, vertical axis turbines arethought to be very inefficient. “Efficiency” is here defined in thestandard way: how much total wind energy impacting the turbine's workingsurfaces gets transformed into rotational energy. Let us suppose ourhypothetical Savonius-type wind turbine makes a poor showing in thisregard and is only 20% efficient. It will only capture 20% of the 1785pounds impacting its vane surfaces for a final total of 357 pounds. Outof a total possible of 5100 pounds striking the 10,000 sq. ft. area, thehypothetical turbine extracts only 357 pounds or 7% total. So far, thatdoesn't sound promising.

How does it compare with an ERDA-NASA propeller turbine? First, let usask the more specific question: “How large a propeller would we need inan ERDA-NASA turbine to capture the same amount of wind force, 357pounds?” Assume we have a turbine with an unrealistically highefficiency rating of 80%. To then capture 357 pounds of wind force, thepropeller would need a total working or capture surface area of357/0.80=446.25 sq. ft. There are three blades to each propeller, so thecapture surface area of each propeller would be 446.25/3=148.75 sq. ft.Making the comparison work even more favorably to the ERDA-NASA unit,let us assume that the three propeller blades are not feathered and thateach blade has an overall average width of 2 ft. In that case, eachblade is a little over 74 ft. long. At this point, we encounter aserious conceptual problem with the initial attempt at comparison. Theblade is approximately the radius of a circular area swept by thepropeller. So, if a propeller has a radius of 74 ft., the circular areait sweeps out is around 17, 203 sq. ft. Unfortunately, that is a muchlarger area than the hypothetical 10,000 sq. ft. we're assuming for thecomparison basis. The conclusion we are driven to given initialassumptions is that one cannot possibly construct an ERDA-NASA propellercapable of extracting the same amount of energy as the hypotheticalSavonius-type turbine in any given area transverse to the wind.

Is it possible to manipulate the figures even more favorable to anERDA-NASA propeller for achieving some basis of comparison? To cut tothe chase, let us first calculate what maximum size ERDA-NASA propellercould be fit into a 10,000 sq. ft. area. Neglecting the need for asupporting tower or any other structures or components (such as thecentral hub), a 10,000 sq. ft. circular area has a radius ofapproximately 56.42 ft. Assume then, that each propeller blade has alength of 56.5 ft. Furthermore, let's give each such propeller an(unrealistic) efficiency rating of 90%. Then, to capture the same 357pounds of wind force, the working surface area of the propeller wouldneed to be 357/0.90=396 sq. ft. Each of the three blades would,therefore, need to have a surface area of 396/3=132 sq. ft. For asurface area of 132 sq. ft. from a propeller blade 56.5 ft. in length,the average width of each blade would need to be 2.34 ft. and completelyunfeathered at all wind speeds. These proportions are at least feasible,even if the other conditions are not. Thus, if we make a comparison withERDA-NASA wind turbines based on several unrealistic assumptions intheir favor, it would still seem to require ERDA-NASA propeller bladesalmost 60 ft. in length and roughly 2.34 ft. in average width, muchwider than normal for this kind of generator.

For another, more realistic comparison, let us suppose that aSavonius-type wind turbine actually presents 40% of its surfaces as windenergy capturing surfaces, a percentage that seems easily achievable.Further, suppose that the hypothetical generator is capable of achieving30% efficiency. Under these still modest assumptions, the total windenergy extracted would be 5100 pounds×40%×30% or 612 total pounds.Further suppose that the ERDA-NASA turbine efficiency is a morerealistic (but still generous) 60%. In that case, the working surfacearea of the propeller, to capture the identical 612 pounds, would needto be 612/0.60=1,020 sq. ft. Each of the three blades would have an areaof 1,020/3=340 sq. ft. As it is unrealistic to assume that thesepropellers have no support structure, let's suppose at least 20% (or2,000 sq. ft., a still modest estimate) of the total 10,000 sq. ft.transverse area of the turbine is committed to area occupied by thesupport tower and/or other auxiliary structures. Then, a propellerswept, circular area of 8,000 sq. ft. would need a radius ofapproximately 50.5 ft. Assuming this as the maximum blade length andgiven the single blade area of 340 sq. ft., each blade would then havean average width of almost 7 ft., always unfeathered, all of which isabsurd given today's conventional ERDA-NASA designs.

What the above comparison illustrates is that the current designs ofERDA-NASA wind turbines, with their relatively narrow, tapered, andoften feathered blades, cannot hope to present sufficientenergy-capturing surfaces to the wind to compete with Savonius-typeturbines. ERDA-NASA turbines would need to undergo significant redesign,greatly increasing blade area through much wider blades, in order tocompete with the wind energy extraction capabilities of knownSavonius-type turbines. The essential point is that while theaerodynamic properties of ERDA-NASA turbines permit them to achievehigher tip-speed ratios, they do so only after sacrificing a vast amountof available wind energy that flows through their rotors untapped.Savonius-type wind turbines present a far greater surface area—adifferential of several magnitudes—for wind energy capture thanERDA-NASA wind turbines of any reasonably comparable size. Theimplication of this disparity in wind energy capture potential is thateven less efficient Savonius-type turbines will always beat out highlyefficient ERDA-NASA turbines in terms of total wind energy harnessed.This startling comparison suggests that methods of wind generator choiceneed to consider more than claimed efficiency ratings. Perhaps a newrating along the lines of “effectiveness of fluid energy extraction”would be more suitable. Efficiency of a device, as typically calculated,is only one measure of the effective transference of available windenergy into rotational mechanical energy. In terms of the generation ofelectrical or pumping energy, it may be the least important. Given thatSavonius-type generators could capture more energy than ERDA-NASAgenerators, easily by a factor of 10, then even the loss of some of thatenergy through transmission devices to yield higher rotational speeds(thus compensating for lower tip-speed ratios) would still producegreater quantities of electricity.

Gravity-flap Savonius turbines designed with the 40% minimum workingsurface of the hypothetical example and with the flap mechanism, purportto yield higher efficiencies than the assumed 30%. Thus, in terms of theeffective and efficient capture of wind energy, this type of turbinecould be highly superior to ERDA-NASA turbines in principle. Theultimate goal in the wind generation of power should be to harvest themaximum possible wind energy available in a given three-dimensionalspace containing wind flow. ERDA-NASA turbines are simply not designedwith that objective in mind.

Unfortunately, the two gravity-flap turbines discussed above, U.S. Pat.No. 5,525,037 and Published Application No. 20040086373, also sufferfrom a feature making them seriously less efficient in capturing windenergy. The main problem with their design is that their gravity-flapvanes are exposed, flat planes. Significant amounts of wind forcestriking the surface can flow laterally off the vane and past their vaneedges. Only a small portion of the wind energy available in striking thevanes would be captured by such designs in contrast with a standard“cup” design which limits lateral wind flow. The assumption made byinventors of those devices is that wind forces impacting theirrespective vanes will strike them with full force and be fully captured.In reality, as in any fluid flow system, blocked vanes will only serveas an obstacle causing a diversion of flow around them. The divertedfluid flow will carry away with it much of the contained fluid flowenergy. Thus, instead of the high energy-capturing efficiency assumed bythe inventors of these gravity-flap devices, the more realisticexpectation should be that the devices will have energy-capturingefficiencies that are much lower. Only if one can trap the fluid flowand prevent lateral flow around the vane can one hope to havesignificant proportions of the fluid energy transferred into a catchmentvane.

Downwind moving, Savonius-type vanes do provide means for trapping fluidflow energy and more effectively capturing the wind energy impinging ontheir concave working surfaces. The wind cannot readily flow sidewaysbut must deliver more of its energy into the vane surface. The concavesurfaces of a Savonius-type vane prevent the easy lateral flow of windaround them. Roughly, the more concave the surface, the more energy thatis not lost to lateral flow and instead gets transferred into the vanesas rotational energy. Of course, as seen above, Savonius-type turbineswith rigid rotor vanes suffer from drag resistance on all but thedownwind part of the cycle (and perhaps even there in principle). Thereis thus a need for a wind turbine able to capture wind energy aseffectively as a Savonius-type wind turbine, with concave surfacesrestricting lateral flow, which can achieve greater efficiency by use ofa gravity-flap system for overcoming drag resistance.

BRIEF SUMMARY OF THE INVENTION

The parent invention combines a Savonius-type design with a gravity-flapdesign for harnessing wind energy effectively and efficiently. Toachieve this, it uses a plurality of roughly rectangularly shaped “cup”vanes which more closely resemble “boxes” than “cups.” Each vane has anopen side in a vertical plane disposed radially outward from the centralvertical axis of rotation and a gravity-flap mounted on its flat rearsurface. These rectangular “box” vanes connect to the central verticalaxis around which they all rotate. The gravity-flap may be made of anylightweight material, such as an aluminum sheet or reinforced fabricstretched over a light frame. The flap is preferably hinged at the topso as to quickly and easily swivel up and down inside the box. The rearsurface of each rectangular vane is left open so that wind may flowthrough when the flap is open.

In operation, wind will flow and be very effectively captured by therectangular box vanes of this invention when open to the direction ofthe wind. The flap in the rear of each vane is slightly larger than therear opening. That flap will be forced closed over the rear openingpreventing wind from flowing through. Thus, the force of the wind willmove the vane, producing torque in the vertical axis. When a vane hasrotated so that it is no longer open to the wind, it will begin toexperience both drag resistance from ambient air and wind forces on therear of the box vane when moving upwind. At those periods in therotation, the force of the wind or resisting air will cause the flap toopen and allow ambient air (or wind) to pass through, decreasing greatlythe resistance from these sources and improving the efficiency of theturbine.

The present invention is an improvement over the prior art. Thisinvention comprises a wind turbine that has its vertical shaft passthrough a support platform. A plurality of braces will be affixed at oneend to this platform, at a preferred angle less than 60 degrees, morepreferably about 45 degrees. With three or more of such braces, windforce leverage effects on the vertical shaft will be reduced resultingin less wear on the vertical shaft bearing(s).

OBJECTS OF THE INVENTION

It is an object of the parent invention to provide a wind turbine whichcan: (a) capture wind energy more effectively and efficiently (asdefined above) than other vertical- or horizontal-axis wind turbines;and (b) convert that energy into rotational energy for running anelectrical generator. The turbine is simple in design, durable even inextreme wind speeds, with almost no moving parts and therefore,cost-effective to build and maintain. In addition, the wind turbine ofthis invention is self-starting. It will accommodate windsomni-directionally from a full 360 degrees without the need for statorblades, stationary or rotating housings to funnel wind, or any othermechanism for favorably orienting the turbine toward the wind.

A further significant object of the parent invention provides a windturbine which is as safe as possible to its operating personnel,property, birds and wildlife. This is accomplished by embodiments inwhich the rotor vanes do not exceed a tip speed ratio of one-to-one forsafer operating speeds and greater visibility (i.e., no “motion smear”from fast-moving blades). While the parent invention has a more compactdesign than ERDA-NASA turbines, its vanes are relatively larger and thusmore visible. The preferred embodiments will use light-weight materialswith blunt edges and rounded surfaces to better cushion potentialimpacts, and one should further note the absence of sharp, fast-movingblades, thin cables, or other parts which otherwise pose safety hazards.It is even feasible to spray coat the surfaces with a rubberized foammaterial to lessen damage from any contact with moving vanes.

It is another object of the parent invention to provide a wind turbinewhich is “stackable.” Multiple units may be placed vertically above oneanother in a suitable framework to increase the amount, andeffectiveness, of wind energy capture by harnessing more wind flow athigher elevations. The parent invention provides a turbine design thatis fully “scalable”: from very large units suitable for the commercialproduction of electrical power; to moderate-sized units for use in ruraldwellings, recreational settings and marine applications; to very smallfolding, portable units suitable for extended duration backpacking ormountain climbing uses. Also, the parent invention will provide a windturbine readily adaptable to running a water pump instead of anelectrical generator. With its safe, compact design, the presentinvention is suitable for operating on the tops of tall buildings.

A principal object of the present invention is to reduce the wind forceleverage effects observed with other wind turbine systems that employ arotating vertical shaft design. Another object is to reduce the effectof bearing wear on such wind turbine systems, regardless of whether suchbearings are located above or below the wind vanes proper and/or betweenmultiple stacked layers of vertical wind vanes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view, ground level schematic showing three of fourwind catchment vanes according to one preferred embodiment of the parentinvention;

FIG. 2 is a perspective schematic showing the four vanes and supportstructure from FIG. 1, along with the direction of wind flow againstsame;

FIG. 3A is a top view schematic of the device in FIG. 2, the dottedlines below each vane indicating the cross-shaped support locatedtherebeneath;

FIG. 3B is a top view schematic of the cross-shaped support and centralrotating vertical axis with the four vanes removed;

FIG. 4 is a front view, ground level schematic showing a firstalternative embodiment of the parent invention in which the vanes (onlythree are shown) connect to a cross-shaped support above;

FIG. 5 is a front view, ground level schematic showing a secondalternative embodiment of the parent invention having vanes that aremore funnel-shaped and taper from an open front to a smaller rear facefor allowing possible wind flow through the center and between opposingvanes;

FIG. 6 is a perspective schematic showing just the four vanes, supportarms and central disk to the FIG. 5 device;

FIG. 7 is a top view schematic from above the device in FIG. 6;

FIG. 8 is a front view, ground level schematic showing a thirdalternative embodiment of the parent invention in which the vanes aresecured to a larger disk with additional supporting struts;

FIG. 9 is a front view, ground level schematic showing a fourthalternative embodiment of the parent invention in which the vanes (onlythree shown) connect to a circular disk, the central hub of which issecurely fastened to an elongated vertical shaft partially enclosed atits base in a freely rotating housing, said shaft connected to anelectrical generator or water pump;

FIG. 10A is a rear view schematic showing one embodiment of vane with arod-weight mechanism hanging down;

FIG. 10B shows an enlarged side view schematic of the rod-weightmechanism of FIG. 10A with a wedge device at the top;

FIG. 10C shows a further enlarged, top view schematic of a wedge shapeatop a rod-weight mechanism;

FIG. 11A is a perspective schematic of one embodiment of vane mademostly from lightweight but heavy gauge “windbreaker” material;

FIG. 11B is a top view schematic of the FIG. 11A vane collapsed ontoitself for compact storage when not in use;

FIG. 11C is a top view schematic of the central vane support wheel forone embodiment of the invention, made from aluminum with supportingstruts and having locking ferrules into which vane prongs may beinserted;

FIG. 11D is a top view schematic of a support rod made from an aluminumtube with expandable locking sections and tapered bottom end showncollapsed for easier stowing;

FIG. 12 is a front view, ground level schematic showing four large unitssimilar to those shown in FIG. 4 or 9 stacked vertically in a supportingframework;

FIGS. 13A, B, C, D and E are side cutaway views schematically depictingalternative box vane shapes and the potentially different wind flowpatterns into and about same;

FIGS. 14A, B and C are side cutaway views schematically depictingalternative box vane depths and the potentially different wind flowpatterns into and about each depth;

FIG. 15 is a front schematic of a representative shaft and bearingshowing a representative wind force effect on same;

FIG. 16 is a front view, ground level schematic of a wind turbine shaftwith angled braces according to one embodiment of the present invention;

FIG. 17 is a perspective schematic showing three vanes and supportstructure with six angled braces on a platform according to a secondembodiment of the present invention;

FIG. 18 is a front view, cutaway schematic of the lower end to the vaneand support structure from FIG. 17; and

FIG. 19 is a top view schematic of the vane and support structure fromFIG. 17 in partial cutaway.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, there is shown a front view, ground level schematicwith three of four wind catchment vanes 2. The fourth vane would beobscured in this view and would be otherwise located behind the vanedepicted in the middle of FIG. 1. At the rear of each box-shaped vane isa gravity-flap 3. The middle vane exhibits its gravity-flap as a dottedline, partially open 4. Each vane is connected at the bottom to across-shaped support base 5. That, in turn, connects to an electricalgenerator 6 set in a steady immovable base 7. A cap 8 covers the cubicalspace in the center of the four vanes of this embodiment attached to theupper inside corner of each vane.

In this embodiment, the front side of each vane 2 is open. Therectangular rear surface of the box-like vane is almost completely openexcept for a narrow flap support rim. Each vane rear opening is coveredby a flap, slightly larger than the opening and normally held down bygravity. Whatever the wind direction, wind force will enter a vanepresenting its larger open side upwind keeping the gravity-flap 3 closedfor that vane. The box-like shape of each vane will funnel wind forcestowards that gravity-flap and prevent lateral escape of the wind. Thiswill transfer wind force into rotational movement of the rotor on whichthe vanes are mounted. However, for the other three vanes which are notpresenting their open sides upwind, there will be air resistance (drag)or wind forces from the wind acting on the rear closed surfaces of each.This will cause the gravity-flaps to open, permitting air or wind toflow through the openings, as is somewhat indicated by the dotted line 4in middle vane. The cross-shaped support base 5 is constructed ofsuitable material, strength and attachment design to support the vanesadequately even in extreme winds. Each vane is constructed ofsufficiently reinforced materials to withstand such conditions. Thesupport base 5 rotates freely about its vertical axis of rotation. Thesupport base 5 connects to the shaft of an electrical generator 6 set ina steady, immovable base 7.

FIG. 2 is a perspective schematic that shows in three dimensions fourvanes 2 on support structure 5. An arrow indicates the direction of windflow against a closed gravity-flap 4 and through openings created bypartially raised gravity-flaps 9. The sides to the vane funnel the windand prevent it from easily escaping laterally. This allows the closedgravity-flap 3 and vane structure to absorb wind energy which thentransforms into rotational motion. Air and wind resistance on the rearsurfaces of the other three vanes raise gravity-flaps 9 and permit airflow through the rear openings in the vanes. This decreases drag orair/wind resistance on the rear surfaces of these vanes, thus increasingefficiency. Note, the leftmost vane L has inside lines drawn for theclosest flap to that vane.

FIG. 3A is a schematic view from above a device having four vanes 2disposed symmetrically about central rotating, vertical axis 10. FIG. 3Bshows the cross-shaped support structure 15 on which the four vanesdepend. The placement of that support is indicated in FIG. 3A by dottedlines below each vane 2. The cap is removed in this view to reveal acubical space 11 created by joining the inside corners of each vane.While the drawing exhibits four opposed vanes, there could bealternative embodiments with three or five vanes with relevantadjustments in support structures. Further research with otherwiseidentical prototypes is necessary to determine if there are any gains ineffectiveness and efficiency as discussed above.

FIG. 4 is a front view, ground level schematic showing a firstalternative embodiment in which the vanes 12 (only three shown) areconnected to a cross-shaped support 25 above, the central hub H of whichsecurely fastens to an elongated vertical shaft 30. Additionalattachments with supporting struts 40 are shown at the top of assembly Aand at the bottom of cubicle space 21 inside the four vanes. Thevertical shaft is partially enclosed at its base in a housing 55 whichit rotates freely. That shaft 30 continues through the base to turn anelectrical generator or water pump 60. This embodiment may be moresuitable for large units in commercial wind farm installations. Also seethe discussion of FIG. 12 below.

FIG. 5 is a front view, ground level schematic showing a secondalternative embodiment. Therein, three of the four wind catchment vanes22 shown are more funnel-shaped, tapering from the open front F to thesmaller rear face R. Also, wind flow is possible through the center ofthe apparatus between opposing vanes. At the narrower rear of eachrectangular shaped vane is a gravity-flap 33. The middle vane exhibitsthe gravity-flap as a partially open dotted line 34. Each vane isconnected by a supporting arm 41 to a round disk structure 35 thatconnects to a secured electrical generator 36 set in a steady, immovablebase 37. The round disk structure 35 rotates freely about its verticalaxis of rotation. Also depicted are support struts 43 attached to thetops of and crossing diagonally between opposed vanes.

FIG. 6 is a perspective schematic of a portion of FIG. 5 showing justthe four vanes 22 and support arms 41 attached to a central disk 35. Anarrow indicates the direction of wind flow against closed gravity-flap33 and through openings created by raised gravity-flaps 39. The taperedsides of the vane funnel the wind and prevent it from easily escapinglaterally. This allows the closed gravity-flap and vane structure toabsorb wind energy for transmission to the rotating disk. Air and windresistance on the rear surfaces of the other three vanes raise theirgravity-flaps 39 and permit air flow through the rear openings in thevanes. This decreases drag or air/wind resistance on the rear surfacesof the vanes, thus increasing efficiency.

FIG. 7 is a top view schematic from above the device in FIG. 6. Thisview shows how four vanes 22 are disposed symmetrically about centralrotating disk 35. Crossing diagonally between opposed vanes are twosupport struts 43. While the preferred embodiment exhibits four opposedvanes, there is no reason that there could not be alternativeembodiments with three or five vanes.

FIG. 8 is a front view, ground level schematic showing a thirdalternative embodiment in which four vanes 62 are secured to a largercircular disk 65 with additional supporting struts 53. That disk 65attaches to a securely anchored, electrical generator 66. Depending onprevailing wind speed conditions and size of the apparatus, thisembodiment may provide more stable rotation with stronger attachmentsbetween the vanes and the rotor than the FIG. 5 embodiment. Each vane 62in FIG. 8 has its own gravity-flap 63 held onto the rear of each vanewith a plurality of spaced apart hinges 60.

FIG. 9 is a front view, ground level schematic of a fourth alternativeembodiment wind turbine in which four vanes 72 (only three shown)connect to a top circular disk 75, the central hub of which securelyfastens to an elongated vertical shaft 70. That shaft is partiallyenclosed at its base in a housing 79 in which it rotates freely, perhapswith ball or roller bearing units. The shaft continues through the baseto turn an electrical generator or water pump 76. The hub H of disk 75has angled supports to provide additional attachment strength andstability. There are also support struts 73 from the top of the verticalshaft 70 to disk 75. The housing 79 is sufficiently reinforced tosupport the superstructure even in extreme wind conditions. In addition,all seals for this embodiment should be covered and weatherproof. Thereare also additional support flanges 80 to attach the rotor vanes to thedisk. This embodiment may be more suitable for large units in commercialwind farm installations. Also see the discussion of FIG. 12 below.

FIG. 10A is a rear view schematic showing one embodiment of vane 92 witha rod-weight mechanism hanging down. FIG. 10B shows an enlarged, sideview schematic of a rod-weight mechanism M with the wedge device W atits top. FIG. 10C shows a further enlarged, top view schematicillustrating the wedge W atop rod-weight mechanism M.

Much attention has been paid in the art to overspeed control mechanismsto prevent damaging the turbine when subjected to excessively highwinds. FIGS. 10A-C depict one alternative for such a device. Thecentrifugal force created by sufficiently high rotation speeds drivesthe weighted mechanism radially outward. This causes the wedge-shapedend W of the mechanism to force the gravity-flap vanes open and spillwind therethrough, thus reducing rotational speed. Other devices alreadyknown in the art could be adapted to this task as well. However, theconception of the present invention is that it will be constructed ofdurable materials sufficient to withstand any wind speeds of reasonableduration likely to be encountered at a given location. Since the designof the present invention exhibits a very high capacity for extractingwind force, it need not be of such a large size compared to existingERDA-NASA wind generators. Using lightweight and reinforced materials ina smaller design will greatly reduce stresses within the system and makepossible the production of units able to withstand extreme wind forces.This should not seriously compromise the capability of the design tomake effective use of low wind speeds. Of course, durability and theresultant added weight will be a tradeoff with effectiveness of windenergy capture at low speeds. Only wind tunnel, or on-site, testing ofprototypes may ultimately determine whether it is more cost-effective totake this approach or introduce overspeed controls, such as this one,into the system.

FIG. 11A is a perspective schematic of one embodiment of vane, generally101, intentionally manufactured to be small, folding or collapsible andportable. It would be made mostly from lightweight (but heavy gauge)“windbreaker” material or fabric about a U-shaped rod 102, preferablymade from fiberglass or aluminum. The latter would be pinned to a swivel103 at each end, then pushed down and held in place with a small Velcrostrap 104. The open face O of vane 101 has fabric secured about a rigidaluminum rod 105 ending in two prongs 106. The rear of the vane is arectangular opening (not seen) covered by a flap 107 of the same fabric,stitched across the top to vane body 108 and secured about anotheraluminum or fiberglass rod at flap bottom 109 so that it is free toswing open and closed.

FIG. 11B is a top view schematic from over a collapsed, folded vaneshowing it as suitable for compact storage when not in use. FIG. 11C isthe central vane support wheel 112 for the apparatus, made of aluminumwith supporting struts, and having four positive locking ferrules 115into which vane prongs like item 106 above may be inserted. The hubbottom 120 of support wheel 112 is a threaded cap which can be screwedclockwise into the top of a support rod 125 shown in a top viewschematic at FIG. 11D. Preferably, hub bottom 120 has a rotating centerfixed to the struts of the support wheel. It engages to a vertical axisshaft in the top of support rod 125. Support rod 125 of FIG. 11D is analuminum tube with three expandable locking sections and a taperedbottom end (shown as collapsed for easier stowing). The top of supportrod 125 contains an electric generator (not seen) which can turn whenthe vane support wheel 112 rotates. At the top two uppermost sections ofsupport rod 125 include a plurality of eyelets 130. These eyelets wouldsecure guy ropes to hold the assembled system down and in place. Insidethe support rod are rechargeable batteries, recharged by the generatorand powering a standard 12V plug 133. When facing high wind conditions,extra cables 140 may be clipped from the outside of vane 101 at an angleto the rim of the vane support wheel to give additional strength andstability to the entire assembly.

Backpacking or mountain climbing expeditions can make use of hand-crankgenerators to provide limited electrical power. However, a lightweightportable wind turbine of the present invention's design may provide amore abundant and steady supply of electricity, especially in the windyconditions of higher elevations. Besides supplying lighting andcommunications power, there may even be enough electrical power from oneunit to allow cooking and using small electric heating devices, thuseliminating lugging along heavy cooking or heating fuel and theinconvenience of using human power to turn a generator crank.

FIG. 12 is a front view, ground level schematic showing four large unitslike those shown and described above for FIG. 4 or 9 stacked verticallywithin a supporting framework 201. Only two of four vanes 202 for eachunit are shown in FIG. 12. Depending on the installation, anypracticable number of units could be stacked in this manner. Thevertical shafts of the units interlock at top and bottom 203 to form ineffect one continuous rotating shaft. Stacking units in this way permitstaking advantage of greater wind velocities at greater heights and alsomultiplies by many times the total amount of wind energy extracted. Thisaccumulation of greater rotational energy allows for the use of largerelectric generators or water pumps at base 204, and makes thisembodiment suitable for commercial wind farm installations. In addition,the framework could be covered with a soft plastic mesh, with a veryopen weave so as not to restrict wind flow, to prevent wildlife fromentering the wind turbines.

FIGS. 13A, B, C, D and E are side cutaway views schematically depictingalternative box vane shapes and the potentially different wind flowpatterns through each. In FIG. 13A, there is shown in partialcross-section, a standard rectangular box shape RB. FIG. 13B shows alarger open front OF face tapering to a smaller rear surface. FIG. 13Cis the reverse of FIG. 13B with a smaller front face SF than rear face.FIGS. 13D and E show alternatives of concavely CV or convexly CX curvedsurfaces, respectively, which could be in combination with any of thethree other box shapes, FIG. 13A 13B or 13C. The issue is which shapesmost efficiently extract wind energy. As shown in these drawings, windflow will be into a given box, laterally across the rear closed flap andthen back out and past the edge of the box vane. A tapered shape such asFIG. 13B may permit less turbulence while within the box, facilitating asmoother flow of wind in and out of the box with less interferencebetween exiting and entering air flows. On the other hand, increasedturbulence inside the box might allow for the better deposit of windenergy into the vane surfaces, a factor offsetting any losses fromentering/exiting air flow interference. In that case, a shape such asFIG. 13C might be better creating greater internal box turbulence. FIGS.13D and E entertain the possibility that curved side surfaces maypromote or dampen turbulence and interference effects and, through moreaerodynamic shaping of wind flow, possibly provide an optimal design forwind energy extraction.

FIGS. 14A, B and C are side cutaway views schematically depictingalternative depths of box vanes and the potentially different wind flowpatterns for same. Clearly, a very shallow box SB, such as FIG. 14A,will not prevent much lateral wind flow and lose significant amounts ofenergy. A very deep box DB such as FIG. 14C, however, will creategreater internal turbulence and entering/exiting interference, whichcould also negatively impact on energy extraction efficiency. FIG. 14Brepresents the “happy medium,” with the ideal box depth HM to bedetermined with the experimental testing of prototypes.

Preferred embodiments of the present invention include a plurality,preferably three or more, roughly rectangularly box-shaped vanesdisposed symmetrically about a vertical axis. These vanes each connectto a common support means. They may also connect, directly or indirectlyto each other. The support means are attached by connecting means to ashort or elongated shaft that rotates about its vertical axis andsupplies power to turn a generator or water pump. The rotation of thevanes is caused by wind force. Each vane has an open front and rear facein vertical planes disposed approximately radially from the verticalaxis. The rear openings of the vanes are covered by rigid lightweightflaps hinged at the top and mounted on the box vane interiors orinsides. These flaps are slightly larger than the rear openings theyadjoin and are normally held down by gravity, hence are called“gravity-flaps.” Whatever the wind direction, wind force will enter avane presenting its open side upwind and keep closed the gravity-flapfor that vane. The box-like shape of each vane will then funnel windforces towards the gravity-flap preventing the wind from laterallyescaping. This will transfer wind forces into a rotational movement ofthe entire vertical axis/rotor. For the other three vanes which are notpresenting their open sides upwind, however, there will be an airresistance (or “drag”) of wind forces from the wind acting on the closedrear surfaces of each vane. That will cause the gravity-flaps to open,permitting air or wind to eventually flow through.

Each vane is preferably connected by suitable supporting material, theultimate strength and attachment design of which will support the vanesadequately even under extreme wind conditions and long-term exposure todiffering weather. Each vane and gravity-flap is constructed ofsufficiently reinforced materials to also withstand these same weathercondition variations.

It is not currently known what shape of box vane, as illustrated inFIGS. 13A-E and/or what box vane depth, as illustrated in FIG. 14A-C,will most efficiently capture wind energy and convert same it torotational energy in the rotor. These may be variable depending onaverage ambient wind speeds and amount of turbulence for a givenlocation. It is also not currently known whether a device with three,four, or five box vanes may yield higher efficiencies, again perhapsdepending on the variables of average wind speed and degree ofturbulence. One may also have to give due consideration to having anopen or closed center region, i.e., between the inside faces ofadjoining vanes. This is seen in the different drawings, with FIG. 1having a closed design and FIG. 5 a more open, flow through design. Theutilization of gravity-flaps in all such designs may significantlyimpact turbulence and air flow patterns within the rotor. Thus, it maynot be possible at this time to adequately predict, in theory, the mostefficient design for a variety of conditions. Only through testing ofexperimental prototypes can such assessments be determined. Thepreferred embodiments will be ones which utilize the optimally efficientshape, depth, number of vanes, and open or closed center areas fordiffering applications and locations.

While all preferred embodiments will make use of strong, lightweightmaterials of sufficient strength, durability, and reinforcement towithstand extreme wind speeds and weather conditions, one embodiment inparticular will emphasize lightness of the overall assembly. Thisembodiment is illustrated by example in FIG. 11. There, the number ofvanes, their overall shape and depth, and whether the design includes anopen or closed center may need to be optimized. Regardless, using alight but strong, wind resistant fabric and light skeletal framework forall components is essential, especially as pertaining to a vane devicewhose box components are intentionally designed to collapse into flat,easily packed and storable forms when not in use.

One major disadvantage of all known solar and wind electric generationsystems is their dependence on a variable source of energy that does notoften coincide with peak electricity demands. Energy storage systems arewell-known in the art, however. For example, U.S. Pat. Nos. 6,023,105and 4,380,419 use wind turbines to drive water pumps rather thanelectric generators per se. The water from these systems can be pumpedto a higher reservoir and then used to run hydroelectric generators viawell understood technology. This allows control of the electricgeneration process to produce electricity when needed.

The present invention is readily adapted to run water pumps instead ofelectric generators. Indeed, water pumps are much less expensive tomanufacture, maintain and replace than electric generators (a costdifferential likely to increase substantially if copper prices continueto soar), and it makes a good deal of sense to employ a system thatminimizes the number of electric generators. A stacked turbine (as seenin FIG. 12) wind farm utilizing the present invention could be installedalong a sea coast and make use of seawater as the pumped fluid insteadof fresh water. In one instance, the lower reservoir could consist ofartificial tidal pools, thus harnessing tidal energy in the first phaseof electric generation. The same concept could be applied to windgenerators on the tops of tall buildings, permitting energy storage inwater tanks at the top of a building before utilizing amini-hydroelectric plant at ground level when demand for electricitygets high.

The parent invention is a safe, compact design that makes it highlysuitable for transportation to and installation on many buildingrooftops. In addition, there is no reason why the electricity producedby such systems could not be diverted (wholly or partially) to otheruses/needs. In the case of coastal seawater installations, some or allof the electricity could be used to run a desalinization plant. Theresultant fresh water could have wind turbine pumping stations along apipeline to carry it to areas of greater need. For tall buildingsystems, the pumped and stored water could be used to supply the freshwater needs of that building and additional water electrically heatedfor the same building's hot water needs. The additional technologiesinvolved, essentially water pump, water tank storage, and hydroelectrictechnologies are simple, well-known and cost-effective.

An alternative system for energy storage would be to use the windturbines described herein to mechanically raise heavy weights ormaterials of any kind from lower to higher elevations instead of usingwater pumps to pump water from a lower to a higher reservoir. Thisalternative system could occur in many embodiments, such as raisingweights along a vertical shaft or “cable car” where heavy, loaded cartscan be raised along an inclined track. When the demand for electricityarises, the heavy weights may be slowly lowered to power an electricgenerator. Such systems might be employed in locales where water sourcesor naturally occurring higher elevations are scarce or unavailable. Forexample, in a sandy desert, artificial inclined dunes might beconstructed with tracks and a cable laid from top to bottom. Containers,such as railcars filled with sand could then be hoisted up these tracksby wind power and the cables used to run generators when the containersare lowered down same. This same invention can easily be used to convertrotational energy to the geared and controlled power transmission formechanically raising weights from lower to higher elevations.

Latest Improvement:

Bearing failure has been a serious problem plaguing the development ofpast vertical-axis wind turbines. Supports, such as guy wires, holdingthe vertical-axis shaft in place produce high levels of stress on thebottom bearing that holds the shaft because that bearing must supportthe weight of the entire wind turbine assembly. If the guy wires areattached to a bearing at the top of the shaft, wind gusts place anadditional downward thrust on the bottom bearing further aggravating theproblem. In addition, pulsating torque usually results from windcatchment of a vertical-axis rotor that is typically asymmetric aroundthe shaft. Only one side of the rotor extracts wind energy in a singlerotation. Such asymmetric wind forces further exacerbate wear andfatigue in bearing mounts.

To better appreciate the effect of asymmetric wind catchment andpulsating torque, it is important to note that bearing loads are furthercompounded by the leverage action exerted on these bearings. This isespecially the case with a long vertical shaft rising some distanceabove the attached vanes on which the wind forces are acting. Even ifthe top of that shaft is secured by a bearing to an upper rigidframework, or supported by guy wires, there will still be some “play” inthe shaft with the asymmetric wind forces multiplied by leverage on thebearing.

FIG. 15 is a front schematic view of a representative shaft and bearingfor showing a typical wind force effect thereon. With respect to FIG.15, suppose the horizontal resultant force of wind on a turbine shaft Sat a given moment is WF1. Suppose further that the distance “d” from WF1to the top of the bearing B is about 10 feet. The top of the bearing B,at point T, will act as a fulcrum. And the underside U, where the shaftS exits through bearing B, will be the load. With a bearing B about 0.5foot high (i.e., the distance between points T and U), the leveragemultiplier for same will be 20. In other words, wind forces with aresultant horizontal vector of, for example, 100 pounds will result in2000 pounds of force concentrated in a very small area of bearing B. Thetops and bottoms of such bearings will both experience excessive weardue to this leveraging of the wind forces on shaft S. With a longvertical shaft, similar leveraging would also be expected to occur onany top bearings.

To address the problem of excessive bearing wear, the aforementionedleverage effects should be counteracted by spreading such forces aroundthe vertical axis base. Referring now to FIG. 16, there is shown onepreferred means for accomplishing same. Support braces 174, at apreferred angle α less than about 60 degrees, can be used to distributesuch forces outward and away from vertical axis shaft 171. Assume thatWF1 is again the resultant force of wind acting on these turbine vanesat a given moment. In that case, the distance “d” from WF1 to the base170 is the same as the distance from the bearings 175 to the outer footof each support brace 174. In that capacity, angle α is then about 45degrees. At that preferred angular ratio, there will be a downward forceD and an upward force E imparted. Such forces will be no greater thanforce WF1, however, as there will be no leverage factor by adding aplurality of angled braces.

FIG. 17 shows, in perspective, a second embodiment of improvedvertical-axis wind turbine according to the present invention. Thissecond embodiment has a vertical-axis shaft 171 attached to six 45degree, angled braces 174. Three representative vanes 173 are affixed tothat shaft 171. In this second preferred embodiment, the support braces174 each connect at their common lower ends to a circular, spoked wheel176. Shaft 171 continues on through an underlying support platform 177to a generator or pump below (not shown). Shaped retaining flanges 178may be used to cover the outside circumference of wheel 176. Frictionreducing devices mounted on wheel 176 under retaining flanges 178 andabove support platform 177 will allow the combined wheel and windturbine assembly to rotate freely thereby counteracting the effect ofasymmetric wind forces on the turbine proper.

FIG. 18 shows in a front view cutaway the lower end to the vane andsupport structure of FIG. 17. Therein, one can better see vertical shaft171 going to the vane attachments region 182 above and generator 183below platform 177. Six 45° support braces 174 (2 of which are shown)connect to shaft 171 above and circular spoked wheel 176 below. Thatcircular spoked wheel 176 rotates on a support platform 177. Retainingflanges 178 (shaped as curved sections) secure to support platform 177and cover the outer circumference of wheel 176. A circular track groove188 runs around the underside of each section of upper flanges. Amatching track groove 189 runs around the top of support platform 177.These grooves accommodate a ball, roller bearing unit or other frictionreducing device, generally 190, mounted at least partially within wheel176. The lower end of shaft 171 runs through a bearing structure 191.That bearing structure is designed to fit loosely around shaft 171 asthe latter will not be subjected to excessive loads.

FIG. 19 shows a top view of the present invention at FIG. 17 with itsvertical shaft 171, outer wheel 176, support platform 177, and pluralityof spokes 192. In FIG. 17, retaining flanges 178 are partially removedto better show representative friction reducing devices 190 mounted towheel 176.

With the improvements of this invention, the vertical shaft will stillneed to pass through a central bearing. It may now be a fairly “loose”fitting, however, with ample play for angled support braces and thelower wheel to absorb most of the loads and system movement. As shown,one embodiment of shaped flanges are sectional for ease of installation,replacement and/or maintenance access. The ball or roller bearing unitsin the wheel may be installed, or easily removed, as complete unitsfurther simplifying their maintenance. Likewise, grooved tracks in thebottom retaining flanges secured to the top support platform may beinstalled in easily removable component sections.

In principle, the circular support wheel and angled braces for thislatest improvement may be of various diameters for potentially removingall leverage forces. Practically speaking, a large diameter supportwheel should not be necessary so long as huge leverage forces arecounteracted to a sufficient extent. While the design in FIGS. 17through 19 show six braces attached at one end to a relatively largediameter support wheel, it may be possible to reduce both the number ofbraces and wheel diameter depending on factors that include overallturbine/vane size and total rotor weight. It is important to note thatthis system will not only counteract most leverage forces, but alsoevenly absorb the weight of the rotor and any additional downwardthrusts resulting from wind forces acting on that rotor.

This system sufficiently addresses the three main factors that are knownto cause undue turbine bearing wear, namely (i) the total weight of therotor, (ii) the downward thrust from wind forces on that rotor; and(iii) the leverage effect of pulsating torque. There may remain otherforces which act on the friction reducing devices in the support wheeland resultant wear. The amount of fatigue and wear should not be assevere as the bearing wear in current vertical-axis designs, however. Inany event, the friction reducing devices of this improvement are moreeasily accessible for maintenance and replacement.

One significant advantage of the present invention is that it will workwell with Gravity-flap Savonius rotors, including the stackedembodiments seen in earlier FIG. 12. A support wheel with braces andretaining flanges may be installed, for each unit, in a vertical stackof rotors. This will prevent undue bearing stress anywhere in a stackedtower of rotors.

An identical, or possibly slightly modified, system could also beinstalled inverted, or upside down at the top of a turbine rotor, tocounteract any leverage effects on the bearing that holds the top of theshaft in place. Since rotor weight and downward thrust forces do not acton that top bearing to the same degree, the addition of top angledbraces may not be as necessary in some applications. As the stresses arefewer, the top supports could also employ a scaled down, smallerdiameter design. In the event top bearings are failing unduly fast,placing such support systems at the top of the rotor would be a viableoption.

EXAMPLES

Prototype models were tested at three ambient wind velocities producedby a fan in closed conditions. The models tested had either three flatsquare vanes or four flat square vanes with gravity flaps, symmetricallydisposed, as the basic configurations. For several runs, sides wereattached to the flat vanes to create relatively shallow boxes in frontof each vane with two different depths, either one-third the length ofthe side of each vane or one-half the length of the side of each vane.In addition, tests were run with the center of the rotor either open orclosed to either permit or prevent, respectively, crossing fluid flowthrough the center of the rotor. Conditions were carefully controlled toensure that the only variables were the number of vanes, the depth ofthe boxes (from 0 for a flat vane to ½ the vane side), and open orclosed centers. Results are tabulated below:

1. Three-Vane Configurations with Gravity Flaps

a. Flat vane (no box), open rotor center

wind velocity RPM low 24.3 medium 44.8 high 57.7

b. Flat vane (no box), closed rotor center

wind velocity RPM low 30.1 medium 47.6 high 54.1

c. Sides with depth of ⅓ vane side, open rotor center

wind velocity RPM low 28.3 medium 48.0 high 61.9

d. Sides with depth of ⅓ vane side, closed rotor center

wind velocity RPM low 31.3 medium 51.3 high 61.9

e. Sides with depth of ½ vane side, open rotor center

wind velocity RPM low 28.4 medium 55.6 high 72.3

f. Sides with depth of ½ vane side, closed rotor center

wind velocity RPM low 31.9 medium 54.1 high 69.0

2. Four-Vane Configurations with Gravity Flaps

a. Flat vane (no box), open rotor center

wind velocity RPM low 25.5 medium 47.6 high 60.6

b. Flat vane (no box), closed rotor center

wind velocity RPM low 25.4 medium 44.4 high 54.1

c. Sides with depth of ⅓ vane side, open rotor center

wind velocity RPM low 31.7 medium 54.1 high 70.1

d. Sides with depth of ⅓ vane side, closed rotor center

wind velocity RPM low 27.1 medium 51.3 high 61.9

e. Sides with depth of ½ vane side, open rotor center

wind velocity RPM low 34.5 medium 56.6 high 71.4

f. Sides with depth of ½ vane side, closed rotor center

wind velocity RPM low 27.3 medium 53.1 high 66.0

The data reveals that significantly better performance could be achievedby box vanes over their flat vane counterparts. Compare 1. a., c., ande. where the only change is from a flat vane (1. a.) to a shallow box of⅓ the vane side (1. c.), to a slightly deeper box of ½ the vane side (1.e.), all three having open rotor centers. At low wind velocity, theboxes produce at least 16% higher RPMs. At high wind velocity, the boxvanes produce as much as 25% higher RPMs. In all trials, there is asmooth correlation for comparable configurations (i.e., all 3 vanes orall 4 vanes/all open center or all closed centers) where the onlyvariable is the flat vane as opposed to box vanes: the deeper the box,the higher the RPM's. Further testing must be done to determine what boxdepth may be the optimal limit, but these tests are sufficient toprovide good evidence that a box vane design is superior to a flat vanedesign for the more effective capture of wind energy.

As far as other variables are concerned, matters are far lessgeneralizable. Contrary to preferences asserted in the two cited patentsfor flat-vane turbines, having a closed rotor center does seem toimprove performance at low wind velocities (though it decreases at highwind velocities) for some three-vane configurations. However, forfour-vane arrangements, a closed rotor center seems to uniformlydecrease performance. The data are quite inconsistent, however, withrespect to three versus four vanes with marginal increases or decreasesor even identical results at different configurations and windvelocities. Since the differences are marginal at best, cost factorsalone may favor using three vanes. A closed center might permit betterstructural strength and compactness making it worth the loss of somewind energy (but offset by using a less heavy structure). Moreover, thetest prototypes and apparatus were designed to permit a fair comparisonof different vane configurations, chiefly flat vs. box, rather thanseeking the optimal arrangement. Further testing with alternativeprototypes might demonstrate that higher numbers of vanes or closedcenters are preferable for some designs.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. One skilled in the art willreadily recognize from such discussion, and from the accompanyingdrawings and claims, that various changes, modifications and variationscan be made therein without departing from the spirit and scope of theinvention.

1. An improved vertical axis wind turbine comprising: (a) a turbinerotor with a support platform, a circular spoked wheel that rotates onsaid support platform, a rotatable vertical shaft that extends at leastpartially through said support platform to an electric generator, atleast one bearing for said vertical shaft, and at least three rotorvanes disposed for rotation about the vertical shaft, each rotor vane:(i) being substantially box-shaped with four solid sides; (ii) having afront-to-rear depth that is at least half its height; and (iii) having afront and rear side disposed in a radial vertical plane, the front sidebeing substantially open faced and the rear side including a narrow rimalong at least three of its sides, each rear side having an openingcovered by a flap that can be moved to an open position with adirectional passage of wind through the rotor vane and to a closedposition with the passage of wind against an interior of the flap; (b)means for attaching each rotor vane to said vertical shaft so that thefront side of each vane lies in the same rotational direction aroundsaid vertical shaft; and (c) a plurality of braces, each brace beingangularly affixed between the circular support wheel and the verticalshaft for reducing wind force leverage effects on the bearing for saidvertical shaft.
 2. The wind turbine of claim 1, wherein said braces areaffixed between the circular support wheel and the vertical shaft at anangle of less than about 60 degrees.
 3. The wind turbine of claim 2,wherein said braces are affixed between the circular support wheel andthe vertical shaft at an angle of about 45 degrees.
 4. The wind turbineof claim 1 which includes at least three braces.
 5. The wind turbine ofclaim 4 which includes six braces equally spaced apart.
 6. The windturbine of claim 1, wherein a plurality of shaped flanges hold anoutside circumference of the circular spoked wheel to the supportplatform.
 7. The wind turbine of claim 6, wherein said wheel supportincludes a plurality of interconnecting track grooves for holdingfriction reducing devices.
 8. In a vertical axis wind turbine thatcomprises: (a) a turbine rotor with a rotatable vertical shaft, at leastone bearing for said vertical shaft, and three to five rotor vanesdisposed symmetrically for rotation about the vertical shaft, each rotorvane: having a front-to-rear depth that is at least half its height;being made from durable lightweight material and being substantiallybox-shaped with four solid sides and a front and rear side disposed in aradial vertical plane, the front side being substantially open faced andthe rear side having a narrow rim along at least three of its sides fordefining an opening covered by a substantially rigid flap that can bemoved with a directional passage of wind through the rotor vane; and (b)means for attaching each rotor vane to the vertical shaft so that thefront side of each vane lies in the same clockwise or counter-clockwisedirection around the vertical shaft, the improvement which comprises:(i) a support platform through which the vertical shaft at leastpartially extends; and (ii) a plurality of braces angularly affixed atone end to a circular spoked wheel that rests on the support plaform andat the other end to the vertical shaft for reducing wind force leverageeffects on said vertical shaft bearing.
 9. The improvement of claim 8,wherein said braces are affixed at an angle less than about 60 degrees.10. The improvement of claim 9, wherein said braces are affixed at anangle of about 45 degrees.
 11. The improvement of claim 8 which includesat least three braces.
 12. The improvement of claim 11 which includessix braces equally spaced apart.
 13. The improvement of claim 8, whereina plurality of shaped flanges hold an outside circumference of thecircular spoked wheel to the support platform.
 14. The improvement ofclaim 13, wherein said wheel support includes a plurality ofinterconnecting track grooves for holding friction reducing devices. 15.The improvement of claim 8, wherein said wind turbine includes aplurality of upwardly extending braces.
 16. The improvement of claim 8,wherein said wind turbine includes a plurality of downwardly extendingbraces.